The present invention provides compounds, pharmaceutical compositions containing one or more of those compounds or their pharmaceutically acceptable salts, which are effective in inhibiting the binding of various chemokines, such as MIP-1α, leukotactin, MPIF-1 and RANTES, to the CCR1 receptor. As antagonists or modulators for the CCR1 receptor, the compounds and compositions have utility in treating inflammatory and immune disorder conditions and diseases.
Human health depends on the body's ability to detect and destroy foreign pathogens that might otherwise take valuable resources from the individual and/or induce illness. The immune system, which comprises leukocytes (white blood cells (WBCs): T and B lymphocytes, monocytes, macrophages granulocytes, NK cell, mast cells, dendritic cell, and immune derived cells (for example, osteoclasts)), lymphoid tissues and lymphoid vessels, is the body's defense system. To combat infection, white blood cells circulate throughout the body to detect pathogens. Once a pathogen is detected, innate immune cells and cytotoxic T cells in particular are recruited to the infection site to destroy the pathogen. Chemokines act as molecular beacons for the recruitment and activation of immune cells, such as lymphocytes, monocytes and granulocytes, identifying sites where pathogens exist.
Despite the immune system's regulation of pathogens, certain inappropriate chemokine signaling can develop and has been attributed to triggering or sustaining inflammatory disorders, such as rheumatoid arthritis, multiple sclerosis and others. For example, in rheumatoid arthritis, unregulated chemokine accumulation in bone joints attracts and activates infiltrating macrophages and T-cells. The activities of these cells induce synovial cell proliferation that leads, at least in part, to inflammation and eventual bone and cartilage loss (see, DeVries, M. E., et al., Semin Immunol 11(2):95-104 (1999)). A hallmark of some demyelinating diseases such as multiple sclerosis is the chemokine-mediated monocyte/macrophage and T cell recruitment to the central nervous system (see, Kennedy, et al., J. Clin. Immunol. 19(5):273-279 (1999)). Chemokine recruitment of destructive WBCs to transplants has been implicated in their subsequent rejection. See, DeVries, M. E., et al., ibid. Because chemokines play pivotal roles in inflammation and lymphocyte development, the ability to specifically manipulate their activity has enormous impact on ameliorating and halting diseases that currently have no satisfactory treatment. In addition, transplant rejection may be minimized without the generalized and complicating effects of costly immunosuppressive pharmaceuticals.
Bone metabolism is dependent on the overall activity of osteoblasts which control bone formation and osteoclasts which control bone resorption. Abnormality of bone metabolism is considered to be caused by an imbalance of the bone formation and the bone resorption. Osteoporosis (and post-menopausal osteoporosis), hypercalcemia, Paget's disease, renal osteodystrophy, rheumtoidarthritis, osteoarthristis, lytic bone metastases, multiple myeloma and the like are known as diseases accompanying abnormality of bone metabolism. Osteoporosis is a typical disease caused by such abnormality of bone metabolism. This disease is generated when bone resorption by osteoclasts exceeds bone formation by osteoblasts. The disease is characterized by a decrease in both the bone calcified material and the bone matrix. CCR1 is believed to play a role in the recruitment of osteoclast precursors and their maturation, and inhibition of this process may amerliorate the disease (Vallet et al, Blood, 110:3744-3752 (2007)). Further sequestration of multiple myeloma cells in the bone marrow leads to the recruitment of osteoclasts to these sites, providing a feedback loop to myeloma proliferation, and stimulating decalcification (Menu et al, Clin Exp Metastases, 23:291-300 (2006)).
Chemokines, a group of greater than 40 small peptides (7-10 kD), ligate receptors expressed primarily on WBCs or immune derived cells, and signal through G-protein-coupled signaling cascades to mediate their chemoattractant and chemostimulant functions. Receptors may bind more than one ligand; for example, the receptor CCR1 ligates RANTES (regulated on activation normal T cell expressed), MIP-1α (macrophage inflammatory protein), MPIF-1/CKβ8, and Leukotactin chemokines (among others with lesser affinities). To date, 24 chemokine receptors are known. The sheer number of chemokines, multiple ligand binding receptors, and different receptor profiles on immune cells allow for tightly controlled and specific immune responses. See, Rossi, et al., Ann. Rev. Immunol. 18(1):217-242 (2000). Chemokine activity can be controlled through the modulation of their corresponding receptors, treating related inflammatory and immunological diseases and enabling organ and tissue transplants.
The receptor CCR1 and its chemokine ligands, including, for example MIP-1α, MPIF-1/CKβ8, leukotactin and RANTES, represent significant therapeutic targets (see Saeki, et al., Current Pharmaceutical Design 9:1201-1208 (2003)) since they have been implicated in rheumatoid arthritis, transplant rejection (see, DeVries, M. E., et al., ibid.), and multiple sclerosis (see, Fischer, et al., J. Neuroimmunol. 110(1-2):195-208 (2000); Izikson, et al., J. Exp. Med. 192(7):1075-1080 (2000); and Rottman, et al., Eur. J. Immunol. 30(8):2372-2377 (2000). In fact, function-blocking antibodies, modified chemokine receptor ligands and small organic compounds have been discovered, some of which have been successfully demonstrated to prevent or treat some chemokine-mediated diseases (reviewed in Rossi, et al., ibid.). Notably, in an experimental model of rheumatoid arthritis, disease development is diminished when a signaling-blocking, modified-RANTES ligand is administered (see Plater-Zyberk, et al., Immunol Lett. 57(1-3):117-120 (1997)). While function-blocking antibody and small peptide therapies are promising, they suffer from the perils of degradation, extremely short half-lives once administered, and prohibitive expense to develop and manufacture, characteristic of most proteins. Small organic compounds are preferable since they often have longer half lives in vivo, require fewer doses to be effective, can often be administered orally, and are consequently less expensive. Some organic antagonists of CCR1 have been previously described (see, Hesselgesser, et al., J. Biol. Chem. 273(25):15687-15692 (1998); Ng, et al., J. Med. Chem. 42(22):4680-4694 (1999); Liang, et al., J. Biol. Chem. 275(25):19000-19008 (2000); and Liang, et al., Eur. J. Pharmacol. 389(1):41-49 (2000)). In view of the effectiveness demonstrated for treatment of disease in animal models (see, Liang, et al., J. Biol. Chem. 275(25):19000-19008 (2000)), the search has continued to identify additional compounds that can be used in the treatment of diseases mediated by CCR1 signaling.